An unsensitized Rh-negative primigravida at 28 weeks presents with painless vaginal bleeding of about 60 mL. Ultrasound excludes placenta previa and abruption, and she is hemodynamically stable. What is the appropriate next step regarding Rh alloimmunization prophylaxis?

• A No anti-D needed because bleeding occurred before 30 weeks
• B Repeat anti-D weekly until delivery regardless of further bleeding
• C Give anti-D only if the fetus is confirmed Rh positive by cell-free DNA
• D Give anti-D immunoglobulin, with the dose guided by Kleihauer-Betke testing ✓

Explanation

Any significant antepartum hemorrhage in an unsensitized Rh-negative woman warrants anti-B immunoglobulin. The standard full antenatal dose of 300 microgram (approximately 1500 IU) protects against fetomaternal hemorrhage up to 30 mL of fetal whole blood, and Kleihauer-Betke testing quantifies larger bleeds so additional doses can be calculated. Waiting for fetal typing delays protection, and gestational age before 30 weeks does not exempt her from prophylaxis.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.