AJR 2004; 183:907-914
© American Roentgen Ray Society
MRI of Right-Sided Abdominal Pain in Pregnancy
Aimee D. Eyvazzadeh1,
Ivan Pedrosa2,
Neil M. Rofsky2,
Bettina Siewert2,
Norman Farrar2,
Jodi Abbott1 and
Deborah Levine1,2
1 Department of Obstetrics and Gynecology, Beth Israel Deaconess Medical Center,
330 Brookline Ave., Boston, MA 02215.
2 Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA
02215.
Received November 21, 2003;
accepted after revision January 30, 2004.
Address correspondence to D. Levine
(dlevine{at}caregroup.harvard.edu).
Introduction
The pregnant patient with right-sided abdominal pain presents a challenge
to the clinician. The pain can be due to causes such as ligamentous laxity or
a hemorrhagic corpus luteum cyst or to conditions that require surgical
intervention such as ovarian torsion or appendicitis. Appendicitis is a
consideration in patients with right-sided pain, even when the pain is not
localized to the lower quadrant because the appendix can be displaced during
pregnancy.
The imaging technique of choice for a pregnant patient who presents with
right lower quadrant pain is currently sonography. There are times, however,
when sonography is not sufficient to make a diagnosis, and correlative imaging
is needed. At our institution, we have recently begun to scan patients with
MRI when appendicitis is clinically suspected. MRI can provide a systematic
cross-sectional view of the anatomic structures and abnormal conditions. This
pictorial essay illustrates normal anatomy and various MRI findings that can
be seen during pregnancy in patients with acute right-sided abdominal
pain.
Technique
Our current MRI protocol includes oral preparation with a combination of
300 mL of silicone-coated superparamagnetic iron oxide (GastroMARK
[ferumoxsil], Mallinckrodt Medical Inc.) and 300 mL of barium sulfate
suspension (Readi-Cat 2, EZ-EM Canada Inc.). This solution is administered 1
hr before the examination in order to ensure filling of the cecum. It provides
negative oral contrast on T1- and T2-weighted images without substantial
susceptibility effect.
MRI examinations are performed on a 1.5-T magnet with a phased-array
surface coil. Our MRI protocol includes T2-weighted imaging with a
non-fat-suppressed half-Fourier single-shot fast spin-echo sequence in the
axial, coronal, and sagittal planes using a 4-mm slice thickness. The time
between acquisitions is approximately 1 sec, and the effective TE is 65 msec.
The field of view is typically 35 cm, and the matrix is 160–192
phase-encoding steps and 256 frequency-encoding steps. A repeat axial
single-shot fast spin-echo sequence is performed using the identical
parameters supplemented by fat saturation to improve the visualization of
periappendiceal inflammatory changes. Axial 2D time-of-flight images are
acquired from the renal veins to the symphysis pubis to screen for a venous
clot and to differentiate the appendix from the frequently encountered
periappendiceal veins. For this sequence, we use TR/TE of 25/minimum with flow
compensation, a field of view of 35 cm, and a matrix of 128 x 256. Axial
dual-echo T1-weighted in- and out-of-phase images are useful for
characterization of hemorrhage or fatty adnexal lesions. For patients with
suspected choledocholithiasis or ureteral stone, a heavily T2-weighted
thick-slab (typically a slice thickness of between 20 and 60 mm) single-shot
fast spin-echo sequence is used
[1].
Safety
MRI is not believed to be hazardous to the fetus. According to the Safety
Committee of the Society for Magnetic Resonance Imaging
[2], MRI procedures are
indicated for use in pregnant women if other nonionizing forms of diagnostic
imaging are inadequate or if the MRI examination provides important
information that would otherwise require exposure to ionizing radiation (e.g.,
X-ray CT).
Indications
Appendicitis
Acute appendicitis is the most common nonobstetrical surgical condition of
the abdomen complicating pregnancy. The incidence of appendicitis in pregnant
women (0.05–0.07%) is similar to that in the general population, but
pregnant patients are more likely to present with perforation (43% vs
4–19% in the general population) because diagnosis tends to be delayed.
Anatomic and physiologic changes that may disguise and delay the diagnosis of
acute appendicitis in pregnant women include a cephalad displacement of the
appendix from the right lower quadrant by the enlarged uterus
[3]; an increased leukocyte
count; and a physiologic increase in maternal blood volume that diminishes the
ability to recognize tachycardia or hypotension.
The normal appendix is seen on MRI as a tubular structure less than 6 mm in
diameter. The presence of air or superparamagnetic oral contrast material
within the lumen of the appendix is visualized as a central hypointense area
in the normal appendix. The normal appendix may be located in a variety of
locations in the right abdomen because the enlarging gravid uterus may
displace the cecum superiorly (Fig.
1A,
1B). We have found that the use
of a cross-referencing function that simultaneously maps position on two or
more images in our PACS facilitates localization of the normal appendix. A
small amount of fluid visualized in the pelvis can be a normal finding.
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Fig. 1A. —Normal appendix in 32-year-old woman at 28 weeks' gestation. Coronal
half-Fourier single-shot fast spin-echo images (TR/TE, single shot/65; matrix,
192 x 256; field of view, 35 cm; and slice thickness, 4 mm) show normal
appendix localized in right upper quadrant (arrowheads, A)
secondary to superior displacement of cecum (C) by enlarged gravid uterus.
Arrow (B) points to tip of appendix.
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Fig. 1B. —Normal appendix in 32-year-old woman at 28 weeks' gestation. Coronal
half-Fourier single-shot fast spin-echo images (TR/TE, single shot/65; matrix,
192 x 256; field of view, 35 cm; and slice thickness, 4 mm) show normal
appendix localized in right upper quadrant (arrowheads, A)
secondary to superior displacement of cecum (C) by enlarged gravid uterus.
Arrow (B) points to tip of appendix.
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MRI findings in appendicitis on T2-weighted imaging include an enlarged
fluid-filled appendix with or without increased signal intensity in the
periappendiceal fat that represents periappendiceal inflammatory changes (Fig.
2A,
2B). A phlegmon may be present
(Fig. 3A,
3B,
3C). In the postappendectomy
patient, inflammatory tissue may be seen around the stump (Fig.
4A,
4B).
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Fig. 2A. —Mild acute appendicitis in 27-year-old woman at 13 weeks' gestation.
Coronal (A) and axial (B) half-Fourier single-shot fast
spin-echo images (TR/TE, single shot/62; flip angle, 130°; matrix, 192
x 256; field of view, 35 cm; and slice thickness, 4 mm) show enlarged
fluid-filled appendix (arrow) measuring 9 mm in diameter. Note
increased signal intensity (arrowheads, A) in mesoappendix
consistent with inflammatory changes. Mild acute appendicitis was confirmed
both at surgery and pathology examination. In B, U = gravid uterus.
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Fig. 2B. —Mild acute appendicitis in 27-year-old woman at 13 weeks' gestation.
Coronal (A) and axial (B) half-Fourier single-shot fast
spin-echo images (TR/TE, single shot/62; flip angle, 130°; matrix, 192
x 256; field of view, 35 cm; and slice thickness, 4 mm) show enlarged
fluid-filled appendix (arrow) measuring 9 mm in diameter. Note
increased signal intensity (arrowheads, A) in mesoappendix
consistent with inflammatory changes. Mild acute appendicitis was confirmed
both at surgery and pathology examination. In B, U = gravid uterus.
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Fig. 3A. —Appendiceal phlegmon in 29-year-old woman at 27 weeks'
gestation. MRI was performed to document size of phlegmon because surgeons
preferred to treat patient with antibiotics if phlegmon was sizeable. Sonogram
reveals heterogeneous mass (arrows) in right lower quadrant in region
of patient's pain, which can be indicative of appendicitis with phlegmon.
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Fig. 3B. —Appendiceal phlegmon in 29-year-old woman at 27 weeks'
gestation. MRI was performed to document size of phlegmon because surgeons
preferred to treat patient with antibiotics if phlegmon was sizeable. Coronal
half-Fourier single-shot fast spin-echo image (TR/TE, single shot /62; flip
angle, 130°; matrix, 192 x 256; field of view, 35 cm; and slice
thickness, 4 mm) shows heterogeneous, moderately hyperintense mass
(arrowheads) in right lower quadrant, consistent with inflammatory
phlegmon.
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Fig. 3C. —Appendiceal phlegmon in 29-year-old woman at 27 weeks'
gestation. MRI was performed to document size of phlegmon because surgeons
preferred to treat patient with antibiotics if phlegmon was sizeable. Axial
fat-saturated half-Fourier single-shot fast spin-echo image (single shot/62;
flip angle, 130°; matrix, 192 x 256; field of view, 30 cm; and slice
thickness, 6 mm) shows markedly enlarged appendix 2 cm in diameter
(arrowheads) surrounded by inflammatory phlegmon. Patient was treated
with IV antibiotics. Follow-up MR image (not shown) obtained 5 weeks later
showed no change. Cesarean delivery was performed at 33 weeks' gestation, and
appendectomy performed at delivery confirmed appendicitis.
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Fig. 4A. —Appendiceal stump in 20-year-old woman with right-sided
abdominal pain and leukocytosis at 21 weeks' gestation. Patient had undergone
appendectomy 13 days before examination. Axial (A) and sagittal
(B) half-Fourier single-shot fast spin-echo images (TR/TE, single
shot/62; flip angle, 130°; matrix, 192 x 256; field of view, 35 cm;
and slice thickness, 4 mm) obtained at level of cecum (C, B) shows
heterogeneously hyperintense masslike appendiceal stump (arrow) with
central high signal intensity due to fluid. Right ovary (arrowhead)
is seen in B.
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Fig. 4B. —Appendiceal stump in 20-year-old woman with right-sided
abdominal pain and leukocytosis at 21 weeks' gestation. Patient had undergone
appendectomy 13 days before examination. Axial (A) and sagittal
(B) half-Fourier single-shot fast spin-echo images (TR/TE, single
shot/62; flip angle, 130°; matrix, 192 x 256; field of view, 35 cm;
and slice thickness, 4 mm) obtained at level of cecum (C, B) shows
heterogeneously hyperintense masslike appendiceal stump (arrow) with
central high signal intensity due to fluid. Right ovary (arrowhead)
is seen in B.
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Gallstones
The incidence of cholelithiasis complicating pregnancy is three per 1,000
live births, with the rate increasing with advancing gestational age.
Screening for gallstones is performed with sonography. In patients in whom
ductal stones are suspected, MR cholangiography offers excellent accuracy for
detecting choledocholithiasis (Fig.
5A,
5B). The stones are visualized
as hypointense filling defects in relation to the adjacent hyperintense bile
on T2-weighted imaging. Stones should be documented on more than one sequence
to ensure that flow artifact is not mistaken for a stone
[4]. ERCP (with its associated
radiation dose) can then be used to treat select patients with documented
stones in the duct.
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Fig. 5A. —36-year-old woman at 35 weeks' gestation with severe right
upper quadrant pain. Lipase level was elevated at 5,342 IU/L. MRI was
performed to assess for obstructing stones and complications of pancreatitis.
Axial half-Fourier single-shot fast spin-echo image (TR/TE, single shot/62;
flip angle, 130°; matrix, 192 x 256; field of view, 35 cm; and slice
thickness, 4 mm) shows diffuse edema in gallbladder wall (arrowheads)
and gallstones (arrow).
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Fig. 5B. —36-year-old woman at 35 weeks' gestation with severe right
upper quadrant pain. Lipase level was elevated at 5,342 IU/L. MRI was
performed to assess for obstructing stones and complications of pancreatitis.
Coronal MR cholangiogram (TR/TE, single shot /1,100; field of view, 35 cm;
matrix, 240 x 256; and slice thickness, 20 mm) shows normal intra- and
extrahepatic bile ducts (small arrows), cystic duct (large
arrow), and pancreatic duct (arrowheads). Patient underwent
laparoscopic cholecystectomy after delivery. Intraoperative cholangiogram (not
shown) showed no stones in bile ducts.
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Renal Causes of Right Lower Quadrant Pain
Ureteral dilatation is commonly present in pregnancy as a result of both
hormonal changes that cause smooth-muscle relaxation and compressive changes
from the enlarging uterus. The right side is typically more dilated than the
left. The ureters are dilated above the level of the pelvic brim and smoothly
taper below this level. Right-sided pain may be caused by hydronephrosis that
can result from an obstructing stone or physiologic hydronephrosis of
pregnancy (Fig. 6A,
6B,
6C,
6D,
6E). The right ovarian vein
complex, which may greatly dilate during pregnancy, lies obliquely over the
right ureter and may contribute to right ureteral dilatation (Fig.
6A,
6B,
6C,
6D,
6E).
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Fig. 6A. —Physiologic hydronephrosis of pregnancy and enlarged right
ovarian vein in 24-year-old woman at 36 weeks' gestation who presented with
abdominal pain just superior to and right of her umbilicus. Coronal (A
and B) and sagittal (C) half-Fourier single-shot fast spin-echo
images (TR/TE, single shot/62; flip angle, 130 °; matrix, 192 x 256;
field of view, 35 cm; and slice thickness, 4 mm) show mild right-sided
hydronephrosis. Enlarged right ovarian vein (arrows, B) is
well visualized as dark tubular structure because of flowing blood. Tapering
ureter (arrowhead, C) just posterior to ovarian vein
(arrow, C) is well visualized.
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Fig. 6B. —Physiologic hydronephrosis of pregnancy and enlarged right
ovarian vein in 24-year-old woman at 36 weeks' gestation who presented with
abdominal pain just superior to and right of her umbilicus. Coronal (A
and B) and sagittal (C) half-Fourier single-shot fast spin-echo
images (TR/TE, single shot/62; flip angle, 130 °; matrix, 192 x 256;
field of view, 35 cm; and slice thickness, 4 mm) show mild right-sided
hydronephrosis. Enlarged right ovarian vein (arrows, B) is
well visualized as dark tubular structure because of flowing blood. Tapering
ureter (arrowhead, C) just posterior to ovarian vein
(arrow, C) is well visualized.
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Fig. 6C. —Physiologic hydronephrosis of pregnancy and enlarged right
ovarian vein in 24-year-old woman at 36 weeks' gestation who presented with
abdominal pain just superior to and right of her umbilicus. Coronal (A
and B) and sagittal (C) half-Fourier single-shot fast spin-echo
images (TR/TE, single shot/62; flip angle, 130 °; matrix, 192 x 256;
field of view, 35 cm; and slice thickness, 4 mm) show mild right-sided
hydronephrosis. Enlarged right ovarian vein (arrows, B) is
well visualized as dark tubular structure because of flowing blood. Tapering
ureter (arrowhead, C) just posterior to ovarian vein
(arrow, C) is well visualized.
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Fig. 6D. —Physiologic hydronephrosis of pregnancy and enlarged right
ovarian vein in 24-year-old woman at 36 weeks' gestation who presented with
abdominal pain just superior to and right of her umbilicus. Axial 2D
time-of-flight image (25/9; flip angle, 30°; matrix, 192 x 256;
field of view, 37 cm; and slice thickness, 3 mm) shows flow in ovarian vein
(arrow).
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Fig. 6E. —Physiologic hydronephrosis of pregnancy and enlarged right
ovarian vein in 24-year-old woman at 36 weeks' gestation who presented with
abdominal pain just superior to and right of her umbilicus. Color Doppler
sonogram shows dilated ovarian vein. This structure should be recognized as
normal variant during pregnancy and may contribute to renal dilatation in
pregnant women. Whether this finding is associated with pelvic pain is
unclear.
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Nephrolithiasis complicates one in 2,000 pregnancies and may lead to
premature labor [5]. The stones
are visualized as hypointense filling defects surrounded by hyperintense urine
on T2-weighted imaging. Care should be taken to not mistake flow artifact for
a stone (Fig. 7A,
7B,
7C). The main limitation of
the MR urography is that resolution tends to be less than optimal, and small
stones can be missed. Unenhanced MR urography has a sensitivity for stones as
low as 54% [6,
7]
(Fig. 8). If space permits in
the magnet bore, it may be helpful to scan the patient in the lateral
decubitus position, with the symptomatic side up to relieve the pressure of
the uterus from the ureter.
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Fig. 7B. —20-year-old woman at 14 weeks' gestation who presented with
right flank pain. Axial (B) and sagittal (C) half-Fourier
single-shot fast spin-echo images (TR/TE, single shot /62; flip angle,
130°; matrix, 192 x 256; field of view, 31 cm; and slice thickness,
4 mm) obtained 4 days after sonogram show central hypointense filling defect
in mid ureter (arrow, B) but no corresponding filling defect
within ureter (arrow, C) at same level on sagittal image.
Moderate hydronephrosis of right kidney (arrowheads, C) is
seen. Multiple similar filling defects noted at different levels on axial
images were believed to be flow-related artifacts. Patient's symptoms
spontaneously resolved without recurrence. Stone seen on sonogram (A)
is not seen on MR images. Either it passed immediately before MRI was
performed or failed to visualize because of low sensitivity of MR urography
for small stones.
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Fig. 7C. —20-year-old woman at 14 weeks' gestation who presented with
right flank pain. Axial (B) and sagittal (C) half-Fourier
single-shot fast spin-echo images (TR/TE, single shot /62; flip angle,
130°; matrix, 192 x 256; field of view, 31 cm; and slice thickness,
4 mm) obtained 4 days after sonogram show central hypointense filling defect
in mid ureter (arrow, B) but no corresponding filling defect
within ureter (arrow, C) at same level on sagittal image.
Moderate hydronephrosis of right kidney (arrowheads, C) is
seen. Multiple similar filling defects noted at different levels on axial
images were believed to be flow-related artifacts. Patient's symptoms
spontaneously resolved without recurrence. Stone seen on sonogram (A)
is not seen on MR images. Either it passed immediately before MRI was
performed or failed to visualize because of low sensitivity of MR urography
for small stones.
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Fig. 8. —31-year-old woman at 24 weeks' gestation who presented with
right lower quadrant pain, nausea, vomiting, and elevated WBC of 24,000
µL. Coronal maximum-intensity-projection image reconstruction from
a multislice coronal half-Fourier single-shot fast spin-echo acquisition
(TR/TE, single shot/62; flip angle, 130°; matrix, 192 x 256; field
of view, 36 cm; and slice thickness, 4 mm) shows moderate hydronephrosis of
right kidney. Note perirenal fluid (arrowheads) indicative of acute
obstruction although no stone was detected. Stone passed day after MRI
examination was performed. F = fetal head.
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Urinary tract infections are common during pregnancy because of urinary
stasis and increased glucose in the urine (Fig.
9A,
9B). Many women with
bacteriuria develop pyelonephritis during pregnancy.
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Fig. 9A. —22-year-old woman at 32 weeks' gestation who presented with
elevated WBC and lower abdominal pain. Findings on previously obtained
sonogram and results of urine dipstick analysis were normal. Axial (A)
and sagittal (B) half-Fourier single-shot fast spin-echo images (TR/TE,
single shot/64; flip angle, 130°; matrix, 192 x 256; field of view,
32 cm; and slice thickness, 4 mm) show low signal intensity in nondependent
portion of urinary bladder (arrows) consistent with air. Patient had
not undergone instrumentation of urinary bladder and, therefore, urinary tract
infection was suggested as cause. MRI findings led to performance of urine
culture that documented presence of Escherichia coli.
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Fig. 9B. —22-year-old woman at 32 weeks' gestation who presented with
elevated WBC and lower abdominal pain. Findings on previously obtained
sonogram and results of urine dipstick analysis were normal. Axial (A)
and sagittal (B) half-Fourier single-shot fast spin-echo images (TR/TE,
single shot/64; flip angle, 130°; matrix, 192 x 256; field of view,
32 cm; and slice thickness, 4 mm) show low signal intensity in nondependent
portion of urinary bladder (arrows) consistent with air. Patient had
not undergone instrumentation of urinary bladder and, therefore, urinary tract
infection was suggested as cause. MRI findings led to performance of urine
culture that documented presence of Escherichia coli.
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Fibroids
Fibroid-related pain in pregnancy may be due to the rapid growth, torsion,
or degeneration of the fibroids. Fibroid degeneration may cause focal pain,
tenderness on palpation, low-grade fever, and leukocytosis. Most often, signs
and symptoms abate within a few days, but inflammation may stimulate labor. In
pregnant patients with abdominal pain secondary to fibroid degeneration, the
diagnosis can be made on sonography by identifying point tenderness when the
probe is place over the fibroid. In complicated cases, MRI can be helpful in
making the diagnosis. Fibroids undergoing hemorrhagic degeneration during
pregnancy typically exhibit diffuse or peripheral high signal intensity on
T1-weighted imaging and variable signal intensity on T2-weighted imaging
[8]. The hyperintense rim on
T1-weighted imaging may correspond to obstructed veins at the periphery of the
mass. Edema can cause diffuse increased signal intensity of uterine fibroids
on T2-weighted imaging and may antedate degeneration
[9] (Fig.
10A,
10B,
10C).
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Fig. 10A. —31-year-old woman at 16 weeks' gestation who presented with
severe right lower quadrant pain. Transabdominal sonogram obtained at level of
right lower quadrant shows exophytic mass (arrows) originating from
right lateral wall of uterus consistent with leiomyoma. Because of clinician's
concern that severe right lower quadrant pain could be due to ovarian torsion
or appendicitis, MRI was performed. P = placenta.
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Fig. 10B. —31-year-old woman at 16 weeks' gestation who presented with
severe right lower quadrant pain. Coronal half-Fourier single-shot fast
spin-echo image (TR/TE, single shot/62; flip angle, 130°; matrix, 192
x 256; field of view, 36 cm; and slice thickness, 4 mm) shows exophytic
mass (arrow) originating from right lateral wall of uterus. Small
amount of free fluid is noted surrounding mass (arrowheads). P =
placenta.
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Fig. 10C. —31-year-old woman at 16 weeks' gestation who presented with
severe right lower quadrant pain. Axial STIR image (4,400/72; inversion time,
175 msec; echo-train length, 33; matrix, 160 x 256; field of view, 22
cm; and slice thickness, 8 mm) shows diffuse heterogeneous increased signal
intensity throughout mass (arrow) suggestive of edema. Free fluid
(arrowheads) around fibroid is well depicted. Fibroid size remained
unchanged throughout pregnancy.
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Hemorrhage
Subchorionic hemorrhage is a frequent cause of bleeding during first and
second trimesters. Small amounts of blood are commonly seen on MRI and do not
necessarily portend a poor prognosis. Hemorrhage can be visualized on
T1-weighted images as areas of high signal intensity (Fig.
11A,
11B). MRI can be used to
detect retroplacental blood in patients with abruption
(Fig. 12).
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Fig. 11A. —Subchorionic hemorrhage in 36 year-old woman at 6 weeks' gestation.
Axial half-Fourier single-shot fast spin-echo image (TR/TE, single shot/62;
matrix, 192 x 256; field of view, 35 cm; and slice thickness, 4 mm)
shows crescent-shaped area (arrow) of low signal intensity between
gestational sac (G) and placenta, suggestive of small subchorionic
hematoma.
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Fig. 11B. —Subchorionic hemorrhage in 36 year-old woman at 6 weeks' gestation.
Axial 3D gradient-echo T1-weighted image (4.5/1.9; matrix, 130 x 256;
field of view, 35 cm; and slice thickness, 2 mm after interpolation) confirms
presence of subchorionic hemorrhage (arrow) with its typical high
signal intensity.
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Fig. 12. —Abruption in patient at 30 weeks' gestation with placenta
previa, bleeding, and pain. Because pain clinically indicates abruption, MRI
was performed to identify extent of retroplacental clot. Immediate delivery
was planned if large abruption was found. Sagittal T1-weighted MR image
(TR/TE, 137/4.1; flip angle, 80°; field of view, 32 cm; matrix, 128
x 256; and acquisition time, 17 sec) shows small clot (arrow)
above internal os (arrowhead), with most of placenta (P) well
attached. Finding allowed patient to be managed expectantly, with
delivery delayed for more than 4 weeks. P = placenta. Reprinted with
permission from [11].
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Adnexal Masses
Most adnexal masses smaller than 6 cm detected during the first trimester
are corpus luteum cysts and resolve spontaneously. If present in the second
trimester, 25% of adnexal masses resolve. One in 1,300 require laparotomy;
2–5% of adnexal masses removed during pregnancy are malignant. Ovarian
masses are typically asymptomatic unless rupture or torsion occurs. Sonography
usually allows the size and consistency of adnexal masses to be determined.
Kier et al. [10] showed that
MRI accurately revealed the origin and nature of the mass and thus decreased
the need for surgery during pregnancy.
If pain is localized to an adnexal mass, torsion is a possibility.
Sonography frequently shows altered blood flow on Doppler sonographic studies.
MRI can depict features suggestive of torsion, such as an enlarged edematous
ovary; however, this finding is not specific for torsion (Fig.
13A,
13B).
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Fig. 13A. —30-year-old woman at 27 weeks' gestation with acute right
lower quadrant pain. MRI was performed to rule out acute appendicitis. Ovarian
torsion was confirmed at laparoscopy. Reprinted with permission from
[12]. Coronal (A) and
sagittal (B) half-Fourier single-shot fast spin-echo images (TR/TE,
single shot/64; flip angle, 130°; matrix, 190 x 256; field of view,
40 cm; and slice thickness, 4 mm) show moderately enlarged right ovary
(arrows) with multiple follicles predominantly located in periphery.
Small amount of free fluid is noted around inferior aspect of right ovary.
Normal appendix is located just inferior to ovary (arrowhead,
A) and is looped on itself.
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Fig. 13B. —30-year-old woman at 27 weeks' gestation with acute right
lower quadrant pain. MRI was performed to rule out acute appendicitis. Ovarian
torsion was confirmed at laparoscopy. Reprinted with permission from
[12]. Coronal (A) and
sagittal (B) half-Fourier single-shot fast spin-echo images (TR/TE,
single shot/64; flip angle, 130°; matrix, 190 x 256; field of view,
40 cm; and slice thickness, 4 mm) show moderately enlarged right ovary
(arrows) with multiple follicles predominantly located in periphery.
Small amount of free fluid is noted around inferior aspect of right ovary.
Normal appendix is located just inferior to ovary (arrowhead,
A) and is looped on itself.
|
|
Conclusion
MRI is increasingly being used to image pregnant patients. Although
pregnant patients with right lower quadrant pain should be initially screened
with sonography, MRI can provide additional valuable information in these
patients. It is important for the radiologist to recognize the MR appearance
of common causes of right-sided pain in pregnancy.
References
- Roy C, Saussine C, LeBras Y, et al. Assessment of painful
ureterohydronephrosis during pregnancy by MR urography. Eur
Radiol 1996;6:334
–338[Medline]
- Shellock FG, Kanal E. Policies, guidelines, and recommendations for
MR imaging safety and patient management: SMRI Safety Committee. J
Magn Reson Imaging 1991;1:97
–101[Medline]
- Baer JL, Reis RA, Arens RA. Appendicitis in pregnancy with changes
in position and axis of normal appendix in pregnancy.
JAMA 1932;98:1359
- Irie H, Honda H, Kuroiwa T, et al. Pitfalls in MR
cholangiopancreatographic interpretation.
Radio-Graphics2001; 21:23
–37[Abstract/Free Full Text]
- Hendricks SK, Ross SO, Krieger JN. An algorithm for diagnosis and
therapy of management and complications of urolithiasis during pregnancy.
Surg Gynecol Obstet1991; 172:49[Medline]
- Roy C, Saussine C, Jahn C, et al. Fast imaging MR assessment of
ureterohydronephrosis during pregnancy. Magn Reson
Imaging 1995;13:767
–772[Medline]
- Sudah M, Vanninen R, Partanen K, Heino A, Vainio P, Ala-Opas M. MR
urography in evaluation of acute flank pain: T2-weighted sequences and
gadolinium-enhanced three-dimensional FLASH compared with urography—fast
low-angle shot. AJR2001; 176:105
–112[Abstract/Free Full Text]
- Murase E, Siegelman ES, Outwater EK, Perez-Jaffe LA, Tureck RW.
Uterine leiomyomas: histopathologic features, MR imaging findings,
differential diagnosis, and treatment. RadioGraphics1999; 19:1179
–1197[Abstract/Free Full Text]
- Ueda H, Togashi K, Konishi I, et al. Unusual appearances of uterine
leiomyomas: MR imaging findings and their histopathologic backgrounds.
RadioGraphics1999; 19[spec no]:S131
–S145
- Kier R, McCarthy SM, Scoutt LM, Viscarello RR, Schwartz PE. Pelvic
masses in pregnancy: MR imaging. Radiology1990; 176:709
–713[Abstract/Free Full Text]
- Trop I, Levine D. Hemorrhage during pregnancy: sonography and MR
imaging. AJR 2001;176
: 607–615[Free Full Text]
- Pedrosa I, Rofsky NM. MR imaging in abdominal emergencies.
Radiol Clin North Am2003; 41:1243
–1273[Medline]
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Introduction
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