In the field of obstetrics, lochia is the vaginal discharge for the first fortnight (fourteen days) of puerperium (after birth), containing blood, mucus, and placental tissue. Lochia discharge typically continues for 4 to 6 weeks after childbirth.^[1]

It progresses through three stages.^[2]

• Lochia rubra (or cruenta) is the first discharge, red in color because of the large amount of blood it contains. It typically lasts no longer than 3 to 5 days after birth.

• Lochia serosa is the term for lochia that has thinned and turned brownish or pink in color. It contains serous exudate, erythrocytes, leukocytes, and cervical mucus. This stage continues until around the tenth day after delivery.
• Sign of late postpartum hemorrhaging: lochia serosa appearing still after a few weeks of birth. Contact physician.

• Lochia alba (or purulenta) is the name for lochia once it has turned whitish or yellowish-white. It typically lasts from the second through the third to sixth weeks after delivery. It contains fewer red blood cells and is mainly made up of leukocytes, epithelial cells, cholesterol, fat, and mucus.

In general, lochia has an odor similar to that of normal menstrual fluid. Any offensive odor indicates contamination by saprophytic organisms and should be reported to a healthcare provider. Lochia that is retained within the uterus is known as lochiostasis^[3] or lochioschesis. Lochiorrhea is the term used when there is abnormal flow of lochia. Composition: Lochia rubra consist of blood,shreds of fetal mebranes and decidua,vernix caseosa,lanugo and meconium.

Lochia serosa consist of less RBC but more leucocytes, wound exudate,mucus from the cervix and microrganisms(anaerobic Streptococci and Staphylococci).The presence of bacteria is not pathognomonic unless associated with clinical signs of sepsis.

Lochia alba contains plenty of decidual cells,leucocytes,mucus,chloestrin crystals,fatty and granular epithelial cells and micro-organisms.

Amount: The average amount of discharge for the first 5-6 days,is estimated to be 250 ml.

Clinical Importance:

• Odour:If offensive,indicates infection.Retained plug or cotton piece inside the vagina should be kept in mind.
• Amount:Scanty or absent-signifies infection or lochiometra.If excessive -indicates infection.
• Colour:Persistence of red color beyond the normal limit signifies subinvolution or retained bits of conceptus.
• Duration:Duration of the lochia alba beyond 3 weeks suggests local genital lesion.

References [link]