Lazio among the worst-hit regions, with hospitals warning that surgery may have to be postponed without more donors coming forward.Italy's National Blood Centre has sounded the alarm over a nationwide shortage of blood, warning that supplies of the O positive group - the most commonly used in transfusions - are running particularly low.  The Centro nazionale sangue (CNS) says the situation is most critical in Lazio, Campania and Sicily. Unusually, no other region currently has a surplus of blood available to redistribute to the areas worst affected, meaning the usual system of compensating shortfalls between regions is under strain.   Summer holidays effect The shortage is a recurring late-summer problem, driven by holidaymakers leaving the capital and donors put off by the heat, even as hospitals continue to need blood for scheduled operations and emergencies year-round.   Rome's Croce Rossa and the Umberto I and Gemelli hospitals have all issued fresh appeals to donors returning from their summer break, warning that a continued shortfall could force the postponement of planned surgery and put urgent transfusions at risk.   CNS director Luciana Teofili said it was too early to give a final assessment of the summer's donations, though inter-regional compensation had worked reasonably well in August. She stressed that the message needed to get through clearly: without blood, operations cannot go ahead, from routine waiting lists to complex surgery. Blood donors Italy relies entirely on unpaid, voluntary blood donation. The country currently has around 1.66 million donors, of whom 1.41 million are regular donors and roughly 250,000 gave blood for the first time last year, according to national data.   About three million donations were made in total, equivalent to roughly 7.5 donations per 100 residents. The 46-55 age bracket accounts for the largest share of donors, while donations among 18-25 year-olds remain the lowest and are in decline.   Donor outreach In response to the alert, Fidas, the national federation of blood donor associations, said it had stepped up efforts to contact donors directly. Federation president Giovanni Musso called on all affiliated groups to intensify donor outreach without delay, working closely with local transfusion services, and appealed in particular to donors with O positive blood.   He also invited regular donors, as well as anyone considering giving blood or plasma for the first time, to get in touch with their local donor association or transfusion service to book an appointment. How to donate in Rome and Lazio Anyone aged between 18 and 70 in good health can donate blood at donation centres and mobile blood units (autoemoteche) across Lazio.   The regional health authority, Salute Lazio, publishes a monthly collection calendar and a list of donation centres on its website. Appointments should be booked directly with the relevant transfusion service or donor association.   Adnkronos and Avis Roma have organised a special donation day in the capital on Thursday 10 September, from 08.30, in Piazza Mastai in Trastevere, open to all Roman residents wishing to give blood.