Correct Answer: A. Cardinal ligament
Uterine prolapse occurs when the pelvic floor support structures fail, allowing the uterus to descend through the vaginal canal. The cardinal ligament (also called transverse cervical ligament) is the primary lateral support structure of the uterus and cervix, extending from the lateral cervix and upper vagina to the lateral pelvic sidewall. It contains smooth muscle, fibrous tissue, and neurovascular bundles and is the most important structure preventing uterine descent. In this G2L2 (gravida 2, live 2) patient delivered at home by untrained dai, prolonged labor, instrumental delivery, or inadequate perineal support during delivery likely caused overstretching and weakening of the cardinal ligament. Damage to this ligament—combined with pelvic floor muscle atrophy from multiple deliveries and lack of proper perineal support—results in loss of lateral uterine support, leading to prolapse. The cardinal ligament is the primary structure assessed clinically for laxity in cases of uterine prolapse, making it the discriminating answer. This is a common presentation in rural India where home deliveries by untrained attendants lack proper management of the third stage of labor and perineal support.
Why the other options are wrong
B. Broad ligament — The broad ligament is a peritoneal fold that envelops the uterus, fallopian tubes, and ovaries but provides minimal structural support for preventing uterine descent. It is primarily a peritoneal reflection, not a true ligament with contractile or supportive tissue. While it may be stretched in prolapse, it is not the primary structure responsible for maintaining uterine position. NBE may include this to trap students who confuse anatomical coverage with functional support. C. Round ligament — The round ligament extends from the uterine fundus through the inguinal canal and terminates in the labia majora. Its primary function is to maintain the anteversion of the uterus, not to prevent vertical descent. Round ligament weakness does not cause prolapse; it may contribute to uterine retroversion if damaged. This is a distractor for students who memorize ligament names without understanding their functional anatomy. D. Uterosacral ligament — The uterosacral ligament extends from the lateral uterine body posteriorly to the sacrum and provides posterior support. While it contributes to pelvic floor support, the cardinal ligament is the primary lateral support structure and the most critical for preventing prolapse. Uterosacral laxity causes retroversion and posterior descent, not the anterior/central prolapse seen in this case. This option tests whether students prioritize cardinal ligament as the main support.
High-Yield Facts
- Cardinal ligament is the primary lateral support structure of the uterus and cervix, containing smooth muscle and fibrous tissue essential for preventing prolapse.
- Uterine prolapse results from weakening of cardinal ligament + pelvic floor muscles + loss of perineal support, commonly seen after traumatic home deliveries.
- G2L2 multiparous women with home deliveries by untrained attendants are at highest risk for prolapse due to repeated pelvic floor trauma and inadequate third-stage management.
- Pelvic floor assessment for prolapse includes testing cardinal ligament laxity by lateral cervical mobility and descent of the cervix on straining.
- Conservative management (pelvic floor exercises, pessary) is first-line for prolapse; Manchester operation or hysterectomy reserved for severe cases in Indian settings.
Mnemonics
SUPPORT for Uterine Position Sacral (uterosacral lig) = posterior support | Uterine (round lig) = anteversion | Pubic (cardinal lig) = LATERAL support (strongest) | Peritoneal (broad lig) = coverage only | Ovary (ovarian lig) = ovarian suspension | Round = fundal anteversion | Transverse cervical = cardinal ligament. Cardinal = strongest lateral support → prolapse when weak. Memory Hook: 'CARDINAL is the CORNERSTONE' Cardinal ligament = transverse cervical ligament = the 'cornerstone' of lateral uterine support. When it fails (trauma, multiparty, poor delivery care), the uterus has no lateral anchor and prolapses. Think: 'cardinal' = 'cardinal direction' = lateral (side-to-side support).
NBE Trap
NBE pairs uterine prolapse with multiple ligament options to trap students who confuse anatomical coverage (broad ligament) with functional support, or who conflate posterior support (uterosacral) with vertical descent prevention. The cardinal ligament's role as the primary lateral support is often underemphasized in rapid revision, making it a high-yield discriminator.
Clinical Pearl
In rural India, untrained dais often fail to provide adequate perineal support during delivery and mismanage the third stage, leading to direct trauma to the cardinal ligament and pelvic floor. A multiparous woman presenting with prolapse after home delivery should prompt immediate assessment of cardinal ligament laxity (lateral cervical mobility on examination) and referral for conservative or surgical management to prevent progression and urinary/fecal complications.
_Reference: DC Dutta's Textbook of Obstetrics (7th ed.), Ch. 18 (Uterine Prolapse); Bailey & Love's Short Practice of Surgery, Ch. 71 (Gynecological Surgery)_