Sacrum
The denominator of a vertex presentation is the occiput (mentum for face, sacrum for breech).
What our notes say
- The denominator of a vertex presentation is the occiput (mentum for face, sacrum for breech). (Junior Clerkship in Reproductive Health (MBOG 4200): end of year examination, 4 )
- L: Legs: the McRoberts manoeuvre (hyperflex the mother's thighs on to the abdomen), which straightens the sacrum and rotates the symphysis. (Junior Clerkship in Reproductive Health (MBOG 4200): end of year examination, 4 )
- • Check for edema behind the malleoli or at the sacrum ( bed ridden patients) (General examination (2) — Past Paper Questions & Answers)
- Typically found along the midline, from skull base to sacrum (Aponeurosis — Embryology Question Bank)
- Pitting oedema → cardinal feature of CCF; press over bony prominence (tibia, lateral malleoli, sacrum) for effective compression (CVS History & Physical Exam: Symptoms, Chest Pain & Syncope)
- Oedema — check behind malleoli; in bedridden patients check the sacrum (General Clinical Examination: Revision Notes & Key Signs)
Study material on Sacrum
Images
Practice questions on Sacrum
A 3-year-old boy has a large vascular mass overlying his sacrum, associated with high-output cardiac failure. Biopsy shows mature vascular channels of arterial and venous type bypassing the capillary bed. What is the diagnosis?
- Infantile hemangioma — benign lesion that eventually regresses
- Cavernous lymphangioma — lymphatic malformation often in the neck
- Sacrococcygeal teratoma with dominant vascular component
- Arteriovenous malformation (AVM) — high-flow shunting causing cardiac strain
Answer: D. Arteriovenous malformations (AVMs) are direct connections between arteries and veins bypassing the capillary bed. Large AVMs (e.g., in sacrum, brain) cause significant high-output cardiac failure due to shunting. ---