The Passage – Maternal Pelvis

Vedant MurkeyBatch 2010

The Journey through the Passage..!!!

• What is PASSAGE (pelvis) composed of..???• What is true and false pelvis..??• Inlet• Cavity• Outlet

BoundariesShapePlaneAxisDiameters

True Pelvis

Inlet Cavity Outlet

Obstetrical Anatomical

The Inlet…!!

• Boundaries --- The Brim• Shape ---

Inlet…!! (contd…)

• Plane

Angle of inclination of pelvic inlet : It is the angle made by plane of the inlet with the horizontal and is normally 55 degrees.

Clinical significance : (In diagram)

• Axis --- Downwards and backwards• Diameters ---

Cavity – THE PLANE OF GREATEST PELVIC DIMENSIONS

• Boundaries --- anteriorly by the posterior

midpoint of pubic symphysisposteriorly by the junction of S2-S3laterally by the upper part of

obturator foramenabove by the brimbelow by the obstetrical outlet

• Shape --- Rounded

• Plane of the greatest dimension (of pelvic cavity)

S2S3

• Axis --- Downwards• Diameters --- later

Obstetrical Outlet..!!!

• Boundaries – Anteriorly is deficientPosteriorly by lower sacral

segmentLaterally by the Ischial bonesAbove is Plane of the Least Pelvic

Dimension (also the plane of obstetrical outlet)Below by the anatomical outlet

• Shape --- Vertically oval• Plane --- plane of least pelvic dimensions.

Extends from lower border of Pubic Symphysis Ischial Spines Tip of the Sacrum. Clinical Significance :1. Internal rotation of head.2. Marks the beginning of forward curve of the

pelvis.3. Landmark used for pudendal block.

• Axis – Almost vertical formed by the line joining the centre of the plane to sacral promomtory.

• Diameters ---

Anatomical outlet…!!!

• Boundaries ---

• Shape --- Diamond shaped bcoz

• Plane ---

• Axis --- Downwards and forwards

Diameters of Pelvis..!!!!

The Pelvic Inlet…!!!1)True Conjugate (TC) – 11cm2)Obstetric Conjugate (OC) – 10 cm3)Diagonal Conjugate (DC) – 12 cm

Only Diagonal Conjugate can be measured clinically by PV examination.OC = DC – 2 cmTC = DC – 1.2 cm

4) Anatomical Transverse Diameter (13 cm)5) Obstetric Transverse Diameter

ATD

OTD

6) Oblique Diameter (12 cm)7) Sacrotyloid Diameter (9.5 cm)

SI Joint

Iliopubic eminence

The Cavity..!!!

• Round cavity of greatest dimensions.• Anteroposterior diameter• Oblique diameter• Transverse diameter

12 cm

Obstetrical Outlet..!!!

• Anteroposterior diameter – from midpoint of sacral promontory to the junction of S2-S3. (11cm)

• Transverse diameter – between two ischial spines. (10.5 cm)

Anatomical Outlet..!!

• Anteroposterior diameter – from the lower border of pubis symphysis ti the tip of coccyx. (13 cm in 2nd stage of labor.)

• Transverse diameter – between two ischial tuberosities. (11 cm)

To summarize..!!!

Diameters Inlet Cavity Outlet - anatomical

Anteroposterior 11 12 13

Oblique 12 12

Transverse 13 12 11

Pelvic Axes…!!!

• Anatomical Axis of Carus… Curved axis formed by joining the axis of inlet, cavity and outlet.

• Obstetrical Axis… Goes downwards and backwards upto level

of ischial spine and abruptly turns forwards.

I had an awesome journey through

the passage.!!Wish u luck for ur

baby…!! :-*