Correct Answer: A. Transverse lie
Uterus didelphys (complete duplication of the uterus with two separate uterine cavities, two cervices, and often a longitudinal vaginal septum) is a Müllerian duct anomaly. The key discriminator is that transverse lie is NOT a complication of this anomaly. Transverse lie occurs when the fetus lies perpendicular to the long axis of the uterus and is typically associated with anomalies that distort the uterine cavity shape or reduce space—such as bicornuate uterus, septate uterus, or uterine fibroids. In uterus didelphys, each uterine cavity is typically normal in shape and size; the anomaly is one of duplication, not distortion. The fetus occupies one normal-shaped cavity and can assume a normal longitudinal lie. Transverse lie is more common in conditions that mechanically restrict fetal positioning (placenta previa, fibroids, contracted pelvis), not in simple duplication. The other complications—endometriosis, abortion, and preterm labor—are well-documented in uterus didelphys due to poor endometrial development, inadequate vascularization, reduced intrauterine space, and impaired myometrial contractility, all of which compromise pregnancy maintenance and fetal growth.
Why the other options are wrong
B. Endometriosis — Endometriosis is a recognized complication of uterus didelphys. The anomaly is associated with abnormal endometrial development, poor vascularization, and altered myometrial function. These factors predispose to retrograde menstruation and implantation of ectopic endometrial tissue. Indian gynecology literature documents increased endometriosis prevalence in Müllerian anomalies, particularly uterus didelphys, making this a true complication. C. Abortion — Spontaneous abortion (miscarriage) is a major complication of uterus didelphys. The reduced intrauterine space, inadequate endometrial development, poor myometrial vascularization, and compromised placentation all increase miscarriage risk. Studies show significantly higher first and second-trimester loss rates in uterus didelphys compared to normal uteri, making abortion a well-established complication. D. Preterm labor — Preterm labor is a documented complication of uterus didelphys due to reduced intrauterine capacity, abnormal myometrial contractility, and inadequate placental development. The smaller cavity size and poor vascularization trigger premature labor. Indian obstetric data confirm increased preterm delivery rates in women with this anomaly, making it a true and clinically significant complication.
High-Yield Facts
- Uterus didelphys = complete duplication with two separate cavities, two cervices, and often longitudinal vaginal septum—NOT associated with transverse lie.
- Transverse lie is a complication of anomalies that distort cavity shape (bicornuate, septate) or reduce space (fibroids, placenta previa), NOT simple duplication.
- Endometriosis, abortion, and preterm labor are all complications of uterus didelphys due to poor endometrial development, reduced intrauterine space, and impaired vascularization.
- Müllerian anomalies classified by ASRM: agenesis, unicornuate, bicornuate, septate, arcuate, and didelphys—each with distinct obstetric risks.
- Fetal positioning in uterus didelphys is typically normal because each cavity is structurally normal; transverse lie requires mechanical obstruction or cavity distortion.
Mnemonics
ASRM Müllerian Anomalies (Class I–VI) I=Agenesis, II=Unicornuate, III=Didelphys/Bicornuate, IV=Septate, V=Arcuate, VI=DES-exposed. Didelphys (Class III) = duplication with normal cavities → normal lie; Septate (Class IV) = distorted cavity → transverse lie risk. Complications of Uterus Didelphys: EAP Endometriosis, Abortion, Preterm labor. NOT transverse lie (that's for bicornuate/septate). Use when ruling out lie complications in didelphys.
NBE Trap
NBE pairs Müllerian anomalies with fetal malpresentation to test whether students distinguish between cavity-distorting anomalies (bicornuate, septate → transverse lie) and cavity-duplicating anomalies (didelphys → normal lie). The trap is assuming all Müllerian anomalies increase malpresentation risk equally.
Clinical Pearl
In Indian obstetric practice, uterus didelphys is often discovered incidentally on ultrasound during pregnancy. The key bedside teaching is: if the fetus is in a normal longitudinal lie with normal amniotic fluid in one cavity, reassure the patient about lie but counsel about increased miscarriage and preterm labor risk—these are the real obstetric threats, not malpresentation.
_Reference: DC Dutta's Textbook of Obstetrics (8th ed.), Ch. 6 "Congenital Anomalies of the Uterus"; ASRM Classification of Müllerian Anomalies (2021 update)_