Female pelvis

for graduate and undergraduate students

1. FEMALE PELVIS By: Maj Saminder Malik MSc (N) Obs & Gyn

2. INTRODUCTION important from obstetric point of view Forms passage for fetus to pass through the birth canal

3. PELVIC BONES Female pelvis is formed by 04 pelvic bones 1. Innominate bones- 2 2. sacrum – 1 3. Coccyx - 1

4. INNOMINATE BONES Consists of 3 parts Ilium Ischium pubis

5. ILIUM Large flared outer part Iliac crest: it is the upper border of ilium and when we place hand on the hip it rest on the iliac crest Iliac spine: the anterior side and posterior side of ilium consists of two bony projections each namely 1. anterior superior iliac spine 2. anterior inferior iliac spine 1 . posterior superior iliac spine 2. posterior inferior iliac spine Iliac fossa: The concave anterior surface of the ilium is the iliac fossa

6. ISHCHIUM It is the thick lower part of innominate bone Ishchial tuberosity: large prominence on which body rest while sitting Ishchial spine: an inward projection behind and above ishchial tuberosity. During labor station of head is estimated in relation to ishchial spine

7. PUBIC BONE Forms the anterior part of innominate bone Body of pubis: thick and flat part of pubic bone Ramii : two arm like projection - superior & inferior Symphysis pubis: the joint between two pubic bones Pubic arch: formed by the infusion of inferior ramii Obturator foramen: space enclosed by pubic ramii , pubic bone and ishchium Sciatic notch: curves on the lower border of innominate bones., for passage of great vessels Greater sciatic notch: extends from posterior inferior iliac spine to the ishchial spine Lesser sciatic notch: between ishchial spine and ishchial tuberosity Acetabulum: deep cup like structure to receive head of femur

8. SACRUM Wedge shaped bone consisting 05 fused vertebrae Sacral promontory: Upper border of 1 st sacral vertebra is known as sacral promontory Ala of sacrum: Lateral side of sacral promontory is known as ala of sacrum or wing of sacrum Halo of sacrum: There are two pairs of holes through which nerves are entering into the pelvic organs

9. COCCYX Vestigial tail Consists of 04 fused vertebral Forms a triangular bone

10. PELVIC JOINTS Sacroiliac Joints= 02 , strongest joints in body , connects sacrum with ilium Sacrococcygeal = 1, base of coccyx articulates with tip of sacrum. Movement of this joint during labor facilitates smooth passage of the baby Symphysis pubis: form at the junction of two pubic bones, united by a pad of cartilage

11. PELVIC LIGAMENTS Each joint is held by the ligaments Sacroiliac ligament: medial surface of ilium to sacrum Sacrospinous ligament: Lateral aspect of the sacrum to ishchial spines Sacrotuberous ligament: Lateral aspect of sacrum to inner aspect of ishchial tuberosity Interpubic ligament: Between two pubic bones Iliolumbar ligament: iliac crest to lumbar vertebrae

12. TYPE OF PELVIS False pelvis True pelvis

13. FALSE PELVIS No obstetric importance Above the pelvic brim / true pelvis Anterior: abdominal wall Posterior: lumbar vertebrae Lateral: iliac crest

14. TRUE PELVIS Bone defined tunnel through which baby has to pass during birth - pelvic brim - pelvic cavity - pelvic outlets

15. PELVIC BRIM Almost round in shape except at the side of sacral promontory Poste: A la or wings of sacrum, sacral promontory Lateral: iliac bones and its lateral borders Anterior : pubic bones Plane of brim is 55 to 60⁰ above the horizontal plane

16. LANDMARKS OF INLET OR BRIM Sacral promontory Ala of sacrum Sacroiliac joint Iliopectineal line Iliopubic eminence Pectineal line Pubic tubercle Pubic crest Symphysis pubis

17. PELVIC CAVITY Above: brim Below: outlet Anterior: pubic bone & pubic symphysis Posterior: curve of sacrum Measurement: 12 cm diameter

18. PELVIC OUTLET Lower part of true pelvis 1. anatomical outlet: Lower borders of each of the bone together with sacrotuberous ligament 2. Obstetrical outlet: diamond shaped AP diameter – sacrococcygeal joint to lower border of symphysis pubis Transverse : between two ishchial spine and two ischial tuberosities

19. PELVIC MUSCLES Inner aspect of bony pelvis is covered with muscle Above the brim: iliac & psoas Side walls: obturator internus and its fascia Posterior: P yriformis Pelvic floor: L evator A nii & C occygenous

20. PELVIC DIAMETERS (INLET) ANTEROPOSTERIOR True Conjugate: from tip of sacral promontory to upper border of symphysis pubis12cm Obstetric conjugate: from tip of sacral promontory to the most bulging point on the back of symphysis pubis (1cm below its upper border)10.5 cm Diagonal Conjugate: from tip of sacral promontory to lower border of symphysis pubis 12-12.5cm TRANSVERSE DIAMETER Two farthest points on iliopectineal lines (4cm from promontory & 7cm from symphysis pubis) largest diameter in pelvis 13cm OBLIQUE DIAMETER sacroiliac joint to iliopectineal eminence 12 cm ( Rt and Lt)

21. PELVIC CAVITY Round All diameters are same 12 cm

22. PELVIC OUTLET Obstetric AP: from tip of sacrum to lower border of symphysis pubis as coccyx moves backwards in 2 nd stage of labor (13cm) Transverse: between ishchial spines (10.5 cm) Anatomical AP: from tip of coccyx to lower border of symphysis pubis Transverse: inner aspect of ishchial tuberosities

23. CLASSIFICATION OF PELVIS Gynecoid pelvis Android pelvis Anthropoid pelvis Platypelloid pelvis

24. GYNAECOID PELVIS Female pelvis 50% females Rounded – slightly oval inlet Straight pelvic sidewalls with roomy pelvic cavity Good sacral curve Ishchial spine not prominent Pubic arch is wide

25. ANDROID PELVIS Male pelvis Pelvic brim is heart shaped convergent sidewalls Narrow pubic arch Prominent spines

26. ANTHROPOID & PLATYPELLOID ANTHROPID Long and narrow pelvic canal AP diameter is more than transverse diameter Straight pelvis side walls PLATYPELLOID 3% women TD is much more than AP diameter Sacral promontory pushed forward

27. IDEAL OBSTETRIC PELVIS Brim: round or oval transversely No undue projection of sacral promontory AP: 12 cm TD: 13cm Plane of pelvic inlet 55degree Cavity: shallow with straight side walls, no great projections of ischial spines and smooth sacral curve Outlet: rounded pubic arch with suprapubic angle more than 80⁰ Intertuberous diameter more than 10cm

28. FAVOURABLE PELVIS Sacral promontory cannot be felt Ischial spine not prominent Suprapubic arch accept 2 fingers Intertuberous diameter accepts 4 knuckles on pelvic exam

29. PELVIC DEFORMITIES

30. PELVIC DEFORMITIES