Most common cause of postpartum hemorrhage?

GMCH Chandigarh - 2022

Obstetrics & Gynaecology

Easy

Appeared in: GMCH Chandigarh - 2022

Explanation

Atonic uterus, or uterine atony, is the most frequent cause of postpartum hemorrhage (PPH), accounting for 70-80% of cases.
It occurs when the uterine myometrium fails to contract effectively after the delivery of the placenta.
This lack of contraction, often felt as a 'boggy' uterus on palpation, leaves the spiral arteries at the former placental attachment site open and bleeding profusely.
The normal mechanism of hemostasis, where the interlacing uterine muscle fibers compress these vessels, fails in uterine atony.

Option A: Bleeding disorders (coagulopathies) correspond to 'Thrombin' in the 4 Ts mnemonic. While they can cause severe bleeding, they are the least common cause of PPH, accounting for only about 1% of cases.
Option B: Abruptio placenta is a primary cause of antepartum (before delivery) hemorrhage. While it is a significant risk factor that can lead to uterine atony or DIC, it is not the most common direct cause of PPH itself.
Option C: Placenta previa, like abruptio placenta, is a leading cause of antepartum hemorrhage. The abnormal placental implantation site can interfere with effective uterine contraction after delivery, making it a risk factor for atony, but atony remains the direct and most common cause.

Visual 1: Diagram: Comparison of a well-contracted postpartum uterus versus an atonic (boggy) uterus, showing compressed versus open spiral arteries at the placental site.
Visual 2: Infographic: The '4 Ts' of Postpartum Hemorrhage (Tone, Trauma, Tissue, Thrombin) with their respective percentages.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of Postpartum Hemorrhage (PPH) as background academic context rather than a clinical decision trigger.
Immediate recognition of a boggy, poorly contracted uterus is a critical nursing assessment. The first-line nursing intervention is vigorous fundal massage to stimulate contraction.
PPH is a leading cause of maternal mortality worldwide, making rapid identification and a standardized, team-based response essential for patient safety.
What if? If initial fundal massage and first-line uterotonics (like oxytocin) fail to control bleeding, the nurse must anticipate and prepare for second-line interventions, including other medications (e.g., carboprost, misoprostol), intrauterine balloon tamponade, and potential surgical procedures, while ensuring large-bore IV access is available for resuscitation.

How to Approach the Question

This is a factual recall question asking for the 'most common' cause of a specific condition.
Identify the key concepts: 'postpartum hemorrhage' and 'most common cause'.
Recall the common causes of PPH, often summarized by the '4 Ts' mnemonic: Tone, Trauma, Tissue, and Thrombin.
Remember that 'Tone' (uterine atony) is the most frequent cause, accounting for the vast majority of cases.
Evaluate the options against this knowledge. 'Atonic uterus' directly corresponds to 'Tone'. 'Bleeding disorders' corresponds to 'Thrombin', which is rare. 'Abruptio placenta' and 'placenta previa' are risk factors but not the most common direct cause.

Concept Tested & Keywords

Concept Tested: Etiology of Postpartum Hemorrhage (PPH)
Stem keywords: postpartum hemorrhage, most common cause
Lead-in keywords: Most common
Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.

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