Women are at risk of serious harm and death because hospitals are not always diagnosing ectopic pregnancies quickly enough, an investigation reveals.

About 12,000 women a year in the UK suffer an ectopic pregnancy – when a fertilised egg grows outside the womb – putting them at risk if a fallopian tube containing the foetus ruptures and causes potentially fatal heavy bleeding.

An inquiry released on Thursday by the NHS’s Healthcare Safety Investigation Branch (HSIB) has found flaws in the treatment women receive. It has highlighted late diagnosis and consequent delay in treatment as a major concern, especially as a result of the condition being mistaken for a urinary tract infection.

NHS patient safety data shows that 30 ectopic pregnancies were missed and led to “serious harm” between April 2017 and August 2018.

As well as the risk to life, an ectopic pregnancy can also damage a woman’s chances of conceiving again and have serious psychological effects.

HSIB’s inquiry was triggered by its investigation into the case of an unnamed 26-year-old woman it called Abby. She attended an NHS minor injuries unit on a Saturday morning complaining of abdominal pain and was referred to an A&E unit.

The doctor there thought she was having a miscarriage and referred her to the hospital’s early pregnancy unit (EPU). Despite ongoing pain it took until the following Tuesday for her to have a trans vaginal ultrasound scan (TVUS), which is the most reliable way of diagnosing an ectopic pregnancy.

By this time her ectopic pregnancy had already ruptured and she had lost a significant amount of blood. She had emergency surgery to remove one of her fallopian tubes.

“Ectopic pregnancy is a common cause of death in early pregnancy and, as Abby’s case highlighted, even if not fatal the effects are distressing and far-reaching. Women can suffer long-term psychological trauma and it can impact on their future fertility”, said Dr Lesley Kay, the HSIB’s deputy medical director.

“If an ectopic pregnancy is diagnosed early it is likely it can be treated effectively and perhaps avoiding the need for invasive surgery.”

Symptoms of an ectopic pregnancy include vaginal bleeding, abdominal pain, shoulder tip pain and discomfort going to the toilet.

The agency, which was set up in 2017 and is modelled on its equivalent body in the airline industry, acknowledged that an ectopic pregnancy can be hard to diagnose.

It has advised the NHS to make changes in order to reduce the risk of delays and thus reduce what Kay called “the devastating risk of severe harm or death in early pregnancy”.

Early pregnancy units are too short-staffed to provide TVUS services as quickly as they are needed, HSIB’s report into minimising harm from ectopic pregnancies concluded.

“There is insufficient capacity to meet the demand for sonography if early pregnancy units are to deliver a seven day a week service.” NHS national bodies should draw up plans to increase staffing so that more scans can be offered, HSIB recommended.

The information pregnant women are given by A&E staff when they are discharged and told to attend the EPU is too variable and needs to be clearer and consistent, the agency also found.

The National Institute of Health and Care Excellence should update its clinical guidance.

Alex Peace-Gadsby, the chair of the Ectopic Pregnancy Trust, welcomed HSIB’s findings, saying: “We often hear of women being misdiagnosed and taking action on the safety recommendations on diagnosis and discharge information in particular will make a big difference in ensuring women get the right care quickly”, she said.

Prof Tim Draycott, a consultant obstetrician and vice president of the Royal College of Obstetricians and Gynaecologists, said: “We are very concerned to hear about any missed ectopic pregnancy as the complications are very serious and can be life threatening. Early diagnosis and treatment is crucial.”