Call the Midwife creator Heidi Thomas has never shied away from some of the most difficult medical conditions to talk about – and in the third episode of series nine, we meet a mother suffering from an obstetric fistula.
Here's what you need to know...
What is a vaginal fistula?
A vaginal fistula is a medical condition where a hole develops between a woman's vagina and either the rectum, bladder, or ureter (the tube between the kidney and the bladder).
As we see in the case of Call the Midwife's Farzina Mohammed (Salma Hoque), this leads to incontinence as the faeces or urine passes through the hole and leaks out of the vagina.
Vaginal fistulas can be caused by an injury, a surgery, a violent rape, an infection, a hysterectomy, or radiation treatment – but an "obstetric fistula" is generally caused by childbirth.
The injury occurs when a prolonged labour presses the unborn child tightly against the pelvis for a long period of time. This can cut off blood flow to the soft tissues, causing the tissue to die ("necrotize") and leaving a hole.
The United Nations Population Fund explains: "Obstetric fistula is one of the most serious and tragic childbirth injuries. A hole between the birth canal and bladder and/or rectum, it is caused by prolonged, obstructed labour without access to timely, high-quality medical treatment. It leaves women leaking urine, faeces or both, and often leads to chronic medical problems, depression, social isolation and deepening poverty."
According to the Fistula Foundation, more than 75% of women with obstetric fistula have endured labour that lasted three days or more.
It is considered a "disease of poverty" and more commonly occurs among women who live in developing countries, who may not have access to medical assistance during a difficult childbirth. After such a protracted ordeal, the baby is usually stillborn.
How is a fistula treated?
With surgery. The hole will need to be closed to separate the vagina from the bladder or rectum.
Where the initial surgery is successful (as in 91% of cases), full continence can be restored. After the operation, physical labour needs to be limited for some months during recovery.
Obstetric fistula can also be prevented from developing in the first place; in fact, the condition has been virtually eradicated in wealthier countries where women have greater access to healthcare and Caesarian sections.
Is the condition considered taboo?
Historically, women who suffered from the condition have been judged harshly and often rejected by society. The taboo and stigma continues today.
The surgery to fix fistulas was first invented in 1852 in America, but unfortunately the vast majority of cases in the world do still go untreated – thanks (in part) to a lack of funds, a shortage of trained surgeons, and minimal awareness of the condition.
Unless they are able to obtain that operation, affected women will face the social stigma of leaking bodily fluids and producing a foul odour. This means many women and girls endure lives of shame, embarrassment, poverty and rejection. Many will also isolate themselves from the community to hide their incontinence.
Call the Midwife continues on Sundays at 8pm on BBC One