JOURNAL OF THE LOUISIANA STATE MEDICAL SOCIETY
RADIOLOGICAL DIAGNOSIS Ruptured pregnancy
Identification of a uterine anomaly may also prompt suspicion for interstitial pregnancy. These are difficult to detect and can mimic an intrauterine pregnancy due to partial implantation in the endometrial cavity. They are surrounded by a layer of myometrium, and have the potential to develop into the early second trimester, increasing the risk for severe hemorrhage.4,8,9 On transvaginal ultrasound, diagnosis is suggested by an empty uterine cavity, an intrauterinegestational sacor decidual reaction located high in the fundus, and a myometrial mantle less than 5 mm.10 The interstitial line sign might also suggest interstitial pregnancy.8,10 Except for an empty uterine cavity, sonographic criteria are only reproducible in the first trimester. It has also been suggested that a thick myometrial bridge separating a twin pregnancy might be unique to heterotopic interstitial pregnancy.11 When ultrasound results are equivocal, MRI can aid in diagnosis but should only be considered in hemodynamically stable patients, as delay of treatment increases the risk of rapid life-threatening blood loss.4,8,9 Uterine rupture and ruptured ectopic pregnancy are medical emergencies that requires prompt treatment of hemodynamic instability and urgent surgical evaluation.4,5 If high a high risk pregnancy is detected early, methotrexate or local injection of potassiumchloride can be used for conservativemanagement of pregnancy in a non-communicating horn or interstitial location. However, use of abortive drugs is contraindicated in heterotopic pregnancy and surgical options should be offered.4,12
CASE REPORT
A 33-year-old woman with a history of twins pregnancy at 16-weeks gestation presented with severe intermittent abdominal pain. Ultrasound at presentation revealed only one viable intrauterine fetus, with the second fetal part seen adjacent to peristalsing bowel. Subsequent MRI showed the non-viable fetal parts inferior to the cecum, as well as a ruptured left uterine horn. Exploratory laparotomy was performed and a bicornuate uterus was identified. The non-viable fetus was removed and the ruptured uterus was repaired. Twin A remained viable and was delivered without complications by cesarian section at 35-weeks gestation.
DISCUSSION
Müllerian duct anomalies are a group of uterine malformations that include arcuate, bicornuate, septate, unicornuate with or without a rudimentary horn, and uterus didelphys.¹ The frequency of having one of these abnormalities is approximately 4%, but the true incidence in the general population is difficult to determine because many patients are asymptomatic with an unremarkable pregnancy course.1,2 While minor defects such arcuate uterus appear to have little impact on obstetric outcome, more pronounced abnormalities have been associated recurrent pregnancy loss, early miscarriage, preterm delivery, preeclampsia, malpresentation, low birth weight, and perinatal mortality.1,3 Uterine rupture in the setting of Müllerian duct anomalies is rare outside of previous cesarean section, but may present as a ruptured ectopic pregnancy implanted in the interstitium or cornu of bicornuate uterus or implantation of the embryo in a non-communicating rudimentary uterine horn.3,4 It is well known that previous cesarean section is the most significant risk factor for uterine rupture and occurs in 1% of women undergoing vaginal birth after cesarean section.5 Rupture of the unscarred uterus is rare, and risk factors include trauma, multiparity, uterine distention, active labor, and use of uterotonic andcervical ripeningdrugs.5,6,7 PatientswithMüllerian duct anomalies are at increased risk for interstitial pregnancy, which results in rupture and life-threatening hemorrhage.4,8 Multiple imaging modalities are available to detect suspected uterine malformations. MRI is currently considered the gold standard for diagnosis, but 3D transvaginal ultrasound has the highest diagnostic accuracy. 2D ultrasound is generally the most common first line study, although sensitivity is only 60%. Hysterosalpingography and saline infusion sonohysterography can also be useful in diagnosis. MRI can differentiate between a muscular or fibrous septum, and can accurately measure the extent to which the septum extends into the uterus. Patient with uterine anomalies are highly associated with renal malformations, thus should prompt kidney evaluation.3
96 La State Med Soc VOL 170 MAY/JUNE 2018
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