fFEMALE PELVIS AND ITS SIGNIFICANCE.pptx

fFEMALE PELVIS AND ITS SIGNIFICANCE

1. THE FEMALE PELVIS AND ITS SIGNIFICANCE LINLY GONDWE Saint JOHN OF GOD UNIVERSITY 12 th August 2025

2. OBJECTIVES Overview of the bony pelvis Describe the structure and divisions of the female pelvis Explain the landmarks and measurements of the bony pelvis Describe the types of female pelvises and their obstetrical significance Explain the functions and significance of the female pelvis

3. INTRODUCTION The female pelvis is a bony canal through which fetus passes during birth The pelvis is lined by fibro – cartilage made up of 4 bones and is held tightly by ligaments The female pelvis is significant to pregnancy and childbirth. The knowledge of the structure, shape and size of the female pelvis is critical to the clinicians and midwives

4. CONT…. Clinicians and midwives should be competent in assessing pelvic findings and their deviations from normal. They should also be able to interpret the significance of the findings to pregnancy and childbirth

5. THE PELVIC BONES The pelvis is made up of four bones namely Two Innominate bones (hip bones) One sacrum One coccyx

6. THE INNOMINATE BONES Each innominate bone is composed of 3 separate bones Ilium Ischium Pubis

7. THE ILIUM A large flared out part of the hip It has a concave anterior surface called Iliac Fossa The margin where the hip rests is called Iliac Crest At the front of the Iliac crest are prominences called anterior superior and anterior inferior Iliac Spines

8. At the back are prominences called posterior superior and posterior inferior Iliac Spines It contributes to 2/5 of the Acetabulum NB : the acetabulum is a deep cup that receives the head of femur

9. ISCHIUM Strongest bone which lies under Ilium and below acetabulum. L shaped bone that’s made up of 2 parts: the body and the ramus. Plays a very important role in leg mobility, balance,standing up and lifting. The ramus of the ischium presents the following land marks Ischial tuberosity: a bony process on the ramus of the ischium at the lower end of the lesser sciatic notch.Gluteous maximus muscle covers the iscial tuberosity.It supports the body when sitting Origin point for hamstring muscles

10. cont Ischial spines Bony prominence between the greater and lesser sciatic notches Provide attachment points for the sacrospinous ligaments and the levator ani muscles Crucial reference point to asses the descent of the presenting part during labour,the station of the fetal head being measured in relation to the level of the ischial spines Lesser sciatic notch- notch on the ramus between the ischial spines and the ischial tuberosity Greater sciatic notch- larger notch located between the posterior inferior iliac spine and the ischial spine

11. THE PUBIS This forms the slightly bowed front portion of the innominate bones. The two pubic bones meet to form a joint called Symphysis Pubis Made up of cartilage and ligaments The cartilage is heavy and is called fibrocartilarge.plays a role by allowing slight separation during labour to help fetus pass through the vagina during delivery

12. THE SACRUM The sacrum is a wedge shaped bone formed by the fusion of five vertebrae It articulates with the lumbar vertebrae above. On the anterior portion is a projection into the pelvic cavity called Sacral Promontory. This projection is an obstetric guide in determining pelvic measurements. The anterior surface is concave and is referred to as Hollow of the Sacrum.

13. THE SACRUM Laterally it extends into wings or alae and it has four pairs of holes –foramina for innervations The posterior surface is roughened for muscle attachment

14. THE COCCYX This is a triangular bone consisting of four vertebrae which may or may not be fused. It articulates with the sacrum at the sacrococcygeal joint. It moves backwards during labour to create more room for the baby

15. THE PELVIC JOINTS There are four pelvic joints One Symphysis Pubis formed by heavy fibrocartilage and anterior and superior pubic ligaments. Joins the two pubic bones. Its mobility increases during pregnancy and causes pain when women walk.

16. THE PELVIC JOINTS Two Sacroiliac Joints Strongest joints between the sacrum and Ilium situated posterioly on either side of the pelvis and are named the right and left sacro iliac joints. It also connects the spine to the pelvis One Sacrococcygeal Joint Lies posteriorly between sacrum and coccyx . Moves backward during labor thus widening outlet.

17. PELVIC LIGAMENTS To fulfill supporting function, the pelvic girdle requires strength and stability and the joints are reinforced by powerful ligaments : Interpubic ligaments at Symphysis pubis Sacroiliac ligaments- strong ligaments which pass in front and behind each sacroiliac joint Sacrococcygeal ligaments The above hold pelvic joints

18. Sacrotuberous ligaments : from the sides of sacrum to the Ischial tuberosities, thus crossing the greater and lesser sciatic notches The Sacrospinous Ligaments : from the sides of sacrum to the Ischial Spines, extending across greater sciatic notches

19. PELVIC DIVISIONS AND MEASUREMENTS The pelvis is divided into two True pelvis False pelvis

20. FALSE PELVIS This is a portion above the pelvic brim It is formed by the upper flared out portions of the Iliac bones It protects abdominal organs but has no significance and helps support the weight of the enlarged uterus

21. TRUE PELVIS This is the portion that lies below the pelvic brim up to the outlet. It has 3 divisions namely The pelvic brim The pelvic cavity The pelvic outlet

22. TRUE PELVIS The true pelvis is extremely significant to childbearing because its size and shape must be adequate for normal fetal passage during labor and birth The relationship of the fetal head to the true pelvic cavity is of critical importance

23. THE PELVIC BRIM Also called pelvic inlet is the upper boarder of the true pelvis It is rounded except where the sacral promontory projects Its has the following significant landmarks Sacral promontory Alae or wings of the sacrum sacroiliac joints

24. THE PELVIC BRIM Also called pelvic inlet is the upper boarder of the true pelvis It is rounded except where the sacral promontory projects An anatomic landmark for assessing whether the fetal head can pass through during delivery.narrow pelvic brim can contribute to complications during delivery Its has the following significant landmarks Sacral promontory Alae or wings of the sacrum sacroiliac joints

25. THE PELVIC BRIM 4 . Ileopectineal line 5. Ileopectineal eminence (roughened area where ramus meet ischium) 6. Superior ramus of the pubic bone 7. Inner boarder of pubic bone 8. Upper inner boarder of the symphysis pubis

26. PELVIC DIAMETERS THE PELVIC BRIM The size and shape of brim is determined by its measurements The brim has three principal diameters; the transverse , the oblique diameter and the anteroposterior diameter ,

27. The Anteroposterior diameters This is from front to back. Extends from the sacral promontory to the symphysis pubis There are three AP diameters (conjugate diameters) Anatomical Conjugate/True conjugate : this is from the sacral promontory to the centre of upper borderof the symphysis pubis and measures 12 cm

28. The Anteroposterior diameters Obstetrical conjugate: from the sacral promontory to the posterior boarder 1.25cm below the upper surface and measures 10.5cm This represents the available space for fetal passage. Diagonal conjugate: from sacral promontory to lower boarder of the symphysis pubis. Its measured on pelvic assessment and should measure 12.5cm on average

29. Oblique Diameters There are two oblique diameters the left and right Arise from sacroiliac joint to ileopectineal eminence of the opposite side. The name depend on the sacroiliac joint it arises. They both measure 12cm

30. Transverse diameter This is from one ileopectineal line of one side to the ileopectineal line of the opposite side It measures 13cm

31. THE CAVITY This extends from the brim to the outlet. The anterior wall is formed by pubic bones and symphysis pubis and its depth is approximately 4cm (some books say 5cm). The posterior wall is formed by the curve of the sacrum which is 12cm (some books say 10cm). It is circular in shape and its exact diameters are difficult to measure. They are all considered to be 12cm .

32. CAVITY The cavity contains the colon, rectum, bladder and some of the reproductive organs The rectum is placed posteriorly in the curve of the sacrum and coccyx The bladder is anterior behind the symphysis pubis

33. THE OUTLET This is the lower boarder of the true pelvis. It is kite or diamond shaped. It can be described as Anatomical outlet: bounded by the lower borders of each bone at the Ischial tuberosity and the sacrotuberous ligaments Obstetrical outlet: includes the narrow pelvic strait of the sacrococcygeal joint, the two Ischial spines and the lower boarder of the symphysis pubis

34. DIAMETERS OF THE OUTLET Anteroposterior diameters From the lower boarder of the symphysis pubis to the sacrococcygeal joint and measures 13cm Oblique diameters Between obturator foramen and sacrospinous ligaments and measures 12cm

35. AP 11 Oblique 12 Transverse 13 12 12 12 13 12 11 Brim Mid cavity Outlet

36. The planes and inclinations of the pelvis Plane of the brim The planes of the pelvis are imaginary flat surfaces taken at different levels through the pelvic canal The main planes are those of the pelvic brim, pelvic outlet and the centre of the pelvic cavity When a woman stands erect the pelvis slopes quite steeply, the anteroposterior iliac spines are in the same plane as the symphysis pubis The plane of the pelvic brim is sloping at an angle of 55 degrees to the horizontal surface The axis of the brim is thus directed backward and outward This is the direction in which the fetal head moves in order to enter the pelvic brim

37. Plane of the cavity This plane lies across the midpoint of the sacrum and pubic bone Internal rotation of head occurs when biparietal diameter occupies this wide pelvic plane Plane of the outlet This slopes at an angle of 15 degrees and is almost horizontal

38. The fetal head follows the axis of each plane It descends in a straight line through the plane of the brim and the plane of the cavity until it reaches the ischial spines

39. TYPES OF PELVIS The Caldwell- Moloy classification of pelvises is widely used and describes the female pelvises as being Gynaecoid pelvis Android pelvis Anthropoid pelvis Platypleoid pelvis

40. GYNAECOID PELVIS Most common 50% Rounded brim Straight sidewalls Curved and short sacrum Blunt Ischial Spines Rounded sciatic notch Sub pubic angle more than 90 degrees

41. ANDROID PELVIS Normal male pelvis. Seen in 20% females Brim is heart shaped Fore pelvis narrow Sacral promontory indented reducing capacity Ischial spines prominent Side wall converge Sacrum long Pubic angle less than 90° Not favorable, descent slow, arrest common, C/S

42. ANTHROPOID PELVIS Occurs in approx 25% Has long oval brim. AP longer than transverse The sidewalls diverge Sub pubic angle more than 90° Ischial Spines blunt Outlet capacity adequate Labor may progress Common in tall women with narrow shoulders

43. PLATYPLEOID PELVIS Flat female pelvis occurs in 5% Kidney shaped brim Side walls are divergent Ischial Spines are usually blunt Labor may progress if head must engage with sagittal suture in the transverse diameter

44. ADEQUACY OF THE PELVIS TO ACHIEVE VAGINAL DELIVERY WHAT IS MEANT BY CLINICALLY FAVORABLE PELVIS Sacral promontory can not be felt Ischial spines are not prominent Sub-pubic arch accept 2 fingers Intertuberous diameter accept 4 knuckles on pelvic exam Obstetric conjugate should be more than 10cm

45. GENERAL FUNCTIONS OF THE PELVIS The pelvis has two major function To support and protect the pelvic organs To form a relatively fixed axis of the birth passage

46. SIGNIFICANCE OF THE FEMALE PELVIS Each portion of the female pelvis has its own significance to pregnancy, labor and delivery. The size & shape of the pelvis has great significance to the progress & outcome of labor Landmarks of the pelvis are useful in determining position and descent of fetus during pregnancy and labor. The fetus is described in relation to the pelvis Knowledge of the pelvis acts as a guide to the midwife in detecting deviation from the normal